House-wiring.



No. 680,834. Patented Aug. 2U, i90l.

F. BATHUBST.

.House wmma.

(Application led Oct. 30, 1899.) (No M adsl.)

'Jl-W] GH'omuu @55k/MM UNITED STATES PATENT OFFICE.

FREDERICK BATHURST, OF SOU'II-IFIELDS, ENGLAND.

HO'USE-WIRING.

SPECIFICATION forming part of Letters Patent N o. 680,884, dated August 2O, 1901. Application filed October 30, 1899. Serial No. 735,340. (No model.)

To @ZZ whom, it may concern:

Be it known that I, FREDERICK BATHURST, a subject of Her Majesty the Queen of Great Britain, residing at Southfelds, in the county of Surrey, England, have invented certain new and useful Improvements in House-Wiring, of which the following is a specification. My invention has for its object the use of a bare wire or bare single-stranded conductor 1o,carried through an armored conduit or lnetallic tube, with a lining or sheath made of any insulating material of an elastic nature as an internal covering. The bare wire or bare stranded conductor in this case forms I5 the positive (-1-) lead, and the metallic tube or armoring is grounded and forms the negative or return-lead. This return-lead is, as aforesaid, grounded, so as to be normally in the condition of ground potential. In the 2o establishment of this system according to my invention it is necessary that all intermediate joint-.boxes and junctions, fittings, and the like may correspond to the conditions of the grounded armored conduit carrying the bare lead. I attain these objects according to the devices illustrated bythe appended drawings and which are referred to in the description.

Figure lis a sectional elevation of a ground- 3o ed armored conduit internally insulated and carrying a bare conductor, showing a plain joint. Fig. 2 is a connection-box adapted to A the same, shown in section, and carrying a tumbler-switch. 3 5 Similar letters refer to similar parts throughout the several views.

In carrying my invention into elfect I elnploy a metal pipe or armored conduit A, Fig. l, which is internally lined or coated with 4o any resilient or elastic insulating lining or sheath B, which may be erected in buildings or the like as an installation in the same manner as ordinary gas or water pipes, with the necessary elbow, T, or socket joints screwed to fit together, and where an open joint is required for breaking the system between g'unction boxes or fittings I employ a running jointthat is to say, having the male screwthread carried back suficiently to clear the 5o sleeves, with a back-nut or lock-nut to close and heremetically seal the joint when completed. It is essential in running an installation upon this system that a perfectly tight joint be made in each junction between lengths ofconduit or when these are broken to admit of connection with junction-boxes and armored casings holding ttings. The perfect continuity of the metallic outer conduit A is essential and also the abutment of the interiorinsulatin g-linin g B. This is effected naturally by the cutting of the conduit or pipe into lengths or at any required point of junction by ordinary pipe-cutters,wl1ich causes the resilient sheath to protrude slightly when the metal is cut. The operation of cutting ascrewthread on the ends increases this, so that when a joint is made the insulating-lining makes a butt-joint, as d, Fig. l, when the sleeve D is screwed home. In order to procure a perfect water-tight joint, I may paint the ends of the pipes with any suitable insulating-varnish to assist the j unction of the insulating-sheathing when in position of abutment. No washers need be employed to edect the junction of the insulating-sheath B. As a matter of fact, the whole of the conduit may be run as a gas or water pipe under the conditions hereinbefore described. The continuity test is carried out by means of a fishing-wire, which is a wire or spiral tape having a weighted end, which being pushed through the bore of B is blocked by any break or obstacle in the continuity thereof, and the position of the same may be exactly located. Said fishing-Wire is always operated by means of a combined rotary and forward movement and serves to guide the bare conductor C through the system of insulated pipes. When said bare conductor C is established, the ordinary tests may be made to determine the relative resistances of the inner bare conductor C and the grounded outer pipe or conduit A, and the hermeticity thereof may be tested as a whole or in sections by an ordinary airpump or like device having a suitable gage or indicator to show any degree of leakage.

All outlets for ceiling-roses, wall-plugs, switches, fuses, andthe like are connected up in the same manner to metal boxes with screwed inlets having an interior insulatinglining similar to and corresponding to the lining B of the conduit or pipe A, the insulating abutment or continuity being preserved.

In the insertion of a switch, which may bc of any type, provided it has a porcelain or like insulating base, but here shown by Fig. 2 as a tumbler-switch, I inclose it Within a case of metal F, which has an insulatinglining B, corresponding to that of the conduit or pipe which is to be fitted thereto. s, forming an integral part of the base F, is screwed to receive a supplementary base R, to which the actual base G of the switch is affixed by the countersunk screws of the terminals t t', and a cover E incloses the switchgear. H ere the bare conductor O passes from terminal tto t', and the circuit is established when the switch is closed, since the case F forms a part of the grounded metallic conduit A.

Having described my invention, -What I claim, and desire to secure by Letters Patent of the United States of America, is as follows:

1. In Wiring electrical installations the combination of a grounded metallic pipe with A stud screwed or like ttings and an insulatingsheath fitting itinteriorly, with a bare single or stranded conductor forming one part of the circuit, and the grounded armored conduit or pipe forming the other part thereof as described and shown.

2. The combination of a grounded metallic pipe With an interior insulating-sheath, a conductor within the said sheath, coupling devices for the said pipe, a case connected t0 the said pipe, an insulating-lining for the interior of the said case and terminals for the said conductor within the said case, the said pipe constituting one part of the electric circuit and the said conductor constituting another part of the same substantially as set forth.

FREDERICK BATHURST. Witnesses:

EDMUN'D S. SNEWIN, WM. O. BROWN. 

